Ten-Port Unitary Optical Processor on a Silicon Photonic Chip

Unitary optical processors (UOPs) are task-specific computing units that can ultimately enable ultrafast and energy-efficient unitary matrix-vector multiplications based on the interference between coherent optical beams. The UOP using multiport directional couplers (MDCs) holds great promise in large-scale integration because of its unique robustness against fabrication errors. Here, we demonstrate a 10-port robust UOP on a silicon photonic chip, which is so far the largest-scale UOP using multiport directional couplers. We further show the unique flexibility of this architecture by demonstrating operations for both the transverse electric (TE) and the transverse magnetic (TM) polarizations, which has never been realized in previous UOPs. This flexible and robust architecture is suitable for various scenarios in deep learning, optical communication, and quantum information processing.